The testing of natural fibers for physical properties has been practiced in industry for many years. Examples of such testing are the measuring of average length and tensile strength of ginned cotton fibers. At the same time, samples are often optically tested for color and trash content. Typically, length and strength testing is carried out on a small sample of fibers extracted from a larger mass which is being analyzed.
One prior system for extracting and holding a small sample of cotton fibers is utilized in the fiber information equipment manufactured by the assignee of this application under the model designations "HVI 3000", "HVI 3500" and "HVI 4000." In such a system, a cylinder-operated, spring biased pinch clamp such as illustrated in FIG. 6 is lowered to the cotton mass. Then, the mechanical force provided by a pneumatic cylinder to maintain the clamp open is withdrawn, causing the spring-loaded clamp to shut, gripping a number of cotton fibers from the mass along the closure line of its jaws. In the HVI systems, the clamp is then used to hold the fibers throughout the remainder of their testing. The steps of combing and brushing are followed by length and strength testing on the fibers, all while held by the clamp. The system works very well, but it will be appreciated that the extracted fibers are taken from a very limited area of the cotton mass, since the pinch clamp operates essentially along a single short line. If the cotton mass exhibits a high degree of non-uniformity, this method of sampling may result in fibers which are not representative of the overall average characteristics of the entire mass from which they are extracted.
Another commercially used sampling system is depicted in U.S. Pat. No. 3,057,019 issued Oct. 9, 1962. In that system, a mass of cotton from which fiber samples are to be extracted is placed by the operator within a foraminous drum. The operator presses the cotton outwardly against the side wall of the drum, causing portions thereof to protrude outwardly through the holes in the drum surface. A rake is rotated around the outside of the drum to impale a sample of fibers on its teeth. This system does, because of its action, extract a sample from a broader physical area than that of the HVI devices discussed above. However, the system involves manual manipulation of the mass of cotton, and the manner in which the fibers are extracted is in part determined by the operator in pressing the cotton mass against the drum wall. As a result, periodic calibrations of the test equipment may be necessary because of inconsistent operator technique in producing the samples. Moreover, at such time as it becomes necessary to remove the fibers from the rake, the removal operation must be carried out manually.
Although the two prior art sampling systems discussed above are widely used in the industry, the advent of the present invention provides a sampling technique which produces representative samples even from a mass of cotton which is relatively heterogeneous. Moreover, the application of the present invention embodies a consistent and automatic sampling of the fibers for testing.